With the rapid development of networks, the demand for Triple play service is becoming increasingly urgent, and when a failure occurs in the network, the operator concerns much about the speed of service convergence. An end-to-end service convergence being conducted within 50 ms when a failure occurs at any node has become a base benchmark for a bearer network.
To meet the requirement that an end-to-end service convergence is conducted within 50 ms, the route fast convergence technologies such as Multi-Protocol Label Switch (MPLS), the Traffic Engineering Fast Re-Routing (TE FRR) and the Interior Gateway Protocol (IGP) have emerged as the times require. However, all these technologies are used for dealing with the fast service convergence or switch upon a link failure within the domain of an Autonomous System, and are not applicable to a link failure between Autonomous System Border Routers (ASBRs). In a practical networking application, a plurality of nodes in one Virtual Private Network (VPN) may be connected to multiple service providers using different Autonomous Systems (ASs), or to multiple as of one service provider. Such a VPN, which is used across a plurality of ASs, is referred to as an Inter-Autonomous System (Inter-AS) VPN.
A conventional technical solution of a fast service convergence upon a link failure between as according to the prior art is described below. Referring to FIG. 1, a schematic diagram of an Inter-AS networking with rectangle connection is shown. When a link failure occurs between ASBR1 and ASBR3, the link failure can be perceived by the ASBR1 and ASBR3 through a link detection method. A route protocol convergence is performed between the ASBR1 and ASBR3 through the Multi-protocol extensions for EBGP 4 (MP-EBGP) protocol, with a need to remove all routes of the Inter-AS VPN routes that have been learned by the ASBR1 and ASBR3 through the MP-EBGP respectively. All of the Provider Edge Device (PE) routers within the domain are notified, through the route protocol of Multi-protocol extensions for IBGP4 (MP-IBGP4) in the domain, that the ASBR1 or ASBR3 with the failure does not have Inter-AS routes any more and can not forward services any more. The PE routers within the domain conduct route convergence and find that some other Inter-AS routers such as ASBR2 and ASBR4 have available routes for the Inter-AS VPN, so the ASBR2 and ASBR4 are reselected as the remote next hop for the Inter-AS service respectively, and are reselected for forwarding. Thus the Inter-AS service is restored.
It can be seen from the above conventional technical solution that, when a link failure occurs between ASs, the service fast convergence is implemented with the method of route re-computation using the convergence of the routing protocol. However, the speed of the convergence of the routing protocol is relatively slow, especially for the Border Gateway Protocol routes transferred by using VPN routing information. According to the current technique level, the convergence time may attain approximate 1 s under the best conditions, while the average level of the converging is between 5 s-10 s. The services such as voice and video expect a convergence time of less than 50 ms, and only if such a switch speed is achieved, the voice and video bearer services will not be affected. Therefore, the time for service switch in the prior art can not meet the requirement for failure switch time of the services such as voice and video.
In addition, for a method using the convergence of a routing protocol, the convergence time is related to the number of the service routes, and the convergence time is increased as the number of the service routes increases greatly.